Knoppix starts in KDE by default. And, KDE comes with Kpackage in the 'system' menu.
Kpackage (KDE native) = Synaptic (Gnome native) [both will work regardless your desktop manager]
Now, if you want to work from the console you can use; dselect (hard to use) and aptitude (not so hard to use) front ends.
 To better understand Debian distributions go to: http://www.debian.org/releases/
I highly recomend you 'apt-spy' to be the first package to install. then at the command line type:
This will scan a BIG list of mirrors, then it will score them acording to the fastest, and update your '/etc/apt/sources.list'. The scan proces will take some time to conclude (like 15 mins)